Attachment plug



May 4 1926.

. P. ROBERTSON ATTACHMENT PLUG Filed Sept. 50, 1921 Patented May 4, 1926.

:f-UNHED STATES PATENT :OFFICE VVWILLIAM r. ROBERTSON, OENEW,YOR1,N.Y., AssIGNOR OEoNE-EALE To W. HAMMOND, OE NEW YORK, N.' Y., lAND ONE-THIRD To THEwATERTOwN MANU-` EACTURINC COMPANY, OE .WATERTOWM CONNECTICUT, A CORPORATION OE CON- NECTICUT. i

ATTACHMENT Emre.

Application area september 30,1921.. seraiNo. 504,503.

To @ZZ Vwhom/fit may concern:

j Bef it4 kno-wn thatv I, WLLIAM; P. .ROBERT- soN, a citizen of the UnitedA States, and a resident' of theV borough vof Ma-nhattan, city, county, and State [of lNew York, have inventedv certain new and useful Improvements in Attachment Plugs, of which the following is a speciflcation.'VV

My inventlon 'relates to a type of electrical devices commonly' .known as attachment plugs whichv are usuallyv attachedv to the end of a exible conductor for` the purpose of connecting an electrical v'device',`such as a lamp, to asource of electricity.'

1 An object of my invention is theV provision of a device of this character which may 4be readily attached, to the u sual'socket or other connecting device withoutthe necessity however, of twisting'- the" plug whereby twisting of'the conductor attachedv to the plug is avoided.

A further object of my invention isthe` provision ofa plug' of the character desig-y nated wherein a' central Contact and an Outer Contact are provided, means being carried by the plug vforforcingthe' outer conj tact into iirm engagement with the socket orl other device withwhich the plug is used.

A further object of my invention is thel provision of 'means .manually V operable for locking the plugl 1in'place when in use.

A further vobject of my inventionis the -provision of anattachment plug wherein V a yielding centralcontact is provided where-' by good Contact will. always be assured.

A still further A'object of my inventionis the provision of an attachment plug vwhich.`

is simple in construction and therefore easy v to manufacture and assemble and wherein the working Vparts are reducedA to a mini- 'mum.

,In the accompanying drawings wherein I have illustrated an embodiment of my inventiO-n,- Fig. 1j represents my improved plugin part sectional elevation, showing thek same i in place in' an ordinary socket; A

Fig. 2 is ak view taken substantially on the line 2&2, of Fig. 1, lookingin the direc# tion of the arrows; v

j Fig. 3 lis a'section taken on the line 3--3 of Fig.'2; y

, Fig. 4 is a front elevation of my impro-ved plugV with the l screw cap with. which the vof closing a' contactlthrough hthe `means of thel member. It 'wouldbe suffiplugV is provided, Removed and front p'artfofthe fplug brokenaway to show ther operating'mechanismy ofthelocking'means l yfor the plug and the means., for; forcing the outer lcontactof the plug into good Contact ,y do

with the side. of a socket; l v

F1g 5- is an .elevation of thelocking means;

Aand .l

. .Fig 6 is avsiden'elevation of Fig. 5.

forcingtheouter contactof the pluginto Vgood lContact withtheside of-'afsocket or other dev icewith which the vplug may be employed,ralso locks the plug inplacein said dViCe, 50i-ht ,the :member shown in Fig; 5 has a double function.

Y Referring -to the-drawings in detail, 1 designates a 'block Offinsulation which may be referredto as'ajbase for improved plug. j This insulating Abase 'iscut away as indicatedlat 2 forthe reception of a locking device 3 which inthe present instance is also of insulationand which locking device, as

above indicated, functionsto `force theouter ber 3. Surrounding the base A1y and the mem- .ber 3 1s an outer Contact 8 of thin brass, for

example, and which' outer Contactv may be crimped as indicated at 9 andlO tov hold the same ill Place on-the base 1. vThey contact 8y is kcut outat 11 so that vthe'outer facev of the member may extend therethrough. Carried withinthe base "1' and secured thereto in ItisV to. be'understood in yconnection with this invention that "the means employed vfor 05 Y y any suitable: manner is a spring'112, this 4 spring backing up the member' and always urging the same outwardly to force a portion of the face .thereof'beyondthe surface of the contact 8 as plainly indicatedin Fig.

3. This projecting portion of the ymember 3V I have designated 13. It'may'here be remarkedl that itis unnecessary'to make the member 3 entirely of insulation, the insulation being provided merelyforfthe purpose cient yfor my purpose, therefore, toinsulate the member 3from the contact 8,

It will be seen fromFig. 3 that the memplug by ber 3 slides on the guideways 6 and'7 already accessible from the exterior of the plug. By f having the member 3` slidablyv mounted as distinguished from a pivotal mounting, the movement of the member 8 necessary to carry it'out of-operativeposition, is lessened. .The base 1 is y,reduced at 15, this reduced yportion being screw-threaded for the reception of an insulated cap lor ring 16 through which the conductors 17 are led.

@The outer contact 8 has an upwardly eX- .tending contracted portion 8 secured to a plate 18 carrying the terminal binding screw 19.r Passing centrally through'the base 1 is a central contact comprising a rod 2O carrying at the lower end thereof l a screwthreaded member 21 constituting the contact proper, this member being adjustable on the rod 2O and sliding in a guideway 22 in the base 1.r Pressing against the upper end of the rod 2O is a spring 23 set into'the top of the base 1, the other end of this spring being constantly in engagement with a conducting plate 24: through which passes a binding post- 25 to which the otherconductor of the pair of conductors 17 is connected. In order that the connections made at the binding posts 19 and 25 may be adequately protected I provide between them an upwardly. extending insulated member 26.

The socket illustrated and one with which my improved plug may be employed is of the usual construction, comprising a screwthreaded inner wall or tube 27 constituting Y a contact, an insulated base 28 and acentral contact 29.

From the foregoing itwill be seen that with my plug in place in the socket electrical connection is established from any suitable source of supply by way of conductor 30, conducting element 31 metal tube contact 27 of the socket, outer contact 8 0f my plug, plate 18, terminal 19, one conductor of the pair of conductors 17 ,l through the device which it may be desired to operate, such as a lamp for example, back through the other conductor of the rpair 17, terminal 25,Y

plate 24, springV 23, rod 20, central contact V21, contact member 29 of the socket, plate 32, to the other conductor 33.

'Io insert my improved plug in its socket it is merely necessary to press inwardly on Athe projection 14: of the insulated member 3v to force the member inwardly radially with respect to the base 1 thereby carrying the face 13 of the member inwardly beyond the face of the o utercontact 8 or flush therewith so that the plug may be readily inserted in the socket. Upon releasing the pressure 1,583,313V Y Y socket, maintain the plug in place therein While I have lshown the projecting portion 13v of the'inember screwthreaded to cooperate with the screw-threaded wall 27 of the socket, it will be understood, of course,

that this is 'not necessary, this showingV having been made by way'iof illustration only. When it is desired to remove the plug from the socket by applying pressure at 111 the member 3 ymay be forced inwardly again to carry the portion 13 thereof out ofi ,contact with the wall of the socket wherebyV the plug may bepulled outwardly.

From the foregoing it will be seen that I have provided an attachment plug which may be inserted intoa socket and locked in place therein without the necessity of rotation of the plug at all whereby twisting of the conductors attached to the plug is avoided and whereby the plug may be inserted in place instantly.

It will be seen also that to remove the plug it is also unnecessary to rotate the n same.

It will be apparent also from the foregoing that I have provided a plug embodying a contact and means carried by the plug V,for forcing this contact into firm engagement with the wall of a socket or vother device with which it is desired to employ the plug ,by causing a bodily movement of the ug. n f

It will be apparent also that I have providedv a plug wherein locking means carried thereby is employed which locking means is movable independently of a contact*V constituting apart of the plug and which locking means is in itself insulated, constituting `no part of an electrical circuit when the device is in use.

While I have illustratedl and described a specific embodiment of my invention, it is to be understood that I am not to be limited thereto inasmuch as various changes may be made in the detailsV of construction and arrangement of parts within the purview of my invention. Y

It is to be further understood that if desired the contact 8 carriedvby the plug could be screw-threaded to conform to the screwthreads on the contactmember 27 y'of the socket.

It is obvious, furthermore, that if desired the member 3 could be Vmounted on the socket instead of upon the plug, the purpose of this member being two-fold as set out above, to wit: for moving the plug bodily so as to bring the contact carried thereby into engagement with' a contactcarryingde` vice such as a socket, and to hold the plug in place therein. Y

What I claim is: y f -l An attachment plug comprising a metallic cylindrical shell having an annular flange at one end thereof, a body portion of insulating material adapted to lie Within said shell, a shoulder portion onA said body portion adapted to engage the iiange on the shell,

an ear connected tothe shell and turned over to bear against the rear face of said body portion to hold the body portion Within the shell, said shell and Vbody portion being provided with a recess,Y the shell overhanging the recess in the body portion there'- Vof defining flanges, an element disposed Within'said recess, resilient means `back of said element Within said recess tending vc to Y move sald elementl out of sald-recess, a plu-V ralityofscrewl threaded formations on the exterior' surface of the element,` andy shoulders ontheelement adaptedto engage with theV flange portions to prevent the element from being moved completely out of said recess by said resilient means.

This` specification signed this 29th day of f Sept., 1921. l p

WILLIAM i?. ROBERTSON; 

